It was discovered that OpenSSL did not always use constant time operations when computing Digital Signature Algorithm (DSA) signatures. A local attacker could possibly use this flaw to obtain a private DSA key belonging to another user or service running on the same system.

Covered now by OpenSSL upstream security advisory and fixed in versions 1.0.1u and 1.0.2i.
Constant time flag not preserved in DSA signing (CVE-2016-2178)
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Severity: Low
Operations in the DSA signing algorithm should run in constant time in order to
avoid side channel attacks. A flaw in the OpenSSL DSA implementation means that
a non-constant time codepath is followed for certain operations. This has been
demonstrated through a cache-timing attack to be sufficient for an attacker to
recover the private DSA key.
OpenSSL 1.0.2 users should upgrade to 1.0.2i
OpenSSL 1.0.1 users should upgrade to 1.0.1u
This issue was reported to OpenSSL on 23rd May 2016 by César Pereida (Aalto
University), Billy Brumley (Tampere University of Technology), and Yuval Yarom
(The University of Adelaide and NICTA). The fix was developed by César Pereida.
External References:
https://www.openssl.org/news/secadv/20160922.txthttp://eprint.iacr.org/2016/594